1. Field of the Invention
The present invention relates to an image display having a liquid crystal cell which is operated by line-sequential scanning of discharge channels, that is, relates to a so-called plasma addressed electro-optical display.
2. Description of Prior Art
The resolution and contrast of a liquid-crystal type display unit have been improved by, for example, a so-called active matrix addressing method, in which an active device, such as a transistor, is provided for each display pixel and the active devices are operated.
The foregoing method, however, must use a multiplicity of semiconductor devices, such as thin-film transistors, thus causing a problem of unsatisfactory low manufacturing yield to arise when a display having a large area is manufactured. Therefore, there arises a problem in that the cost cannot be reduced.
To solve the foregoing problem, a method has been suggested which employs discharge plasma as active devices in place of the semiconductor devices, such as MOS transistors and thin-film transistors.
An image display apparatus (hereinafter called a "plasma addressed electro-optical display") arranged to operate liquid crystal by using discharge plasma has a stacked structure composed of a liquid crystal material layer, which is an electro-optical material layer, and a plasma cell, in which plasma discharge takes place. A thin dielectric-material plate made of glass or the like is disposed between the liquid crystal layer and the plasma cell.
The plasma addressed electro-optical display has a structure in which the plasma cell is divided into linear plasma chambers by barrier ribs. The plasma chambers are sequentially switched and scanned, and signal voltages are synchronously applied to transparent electrodes opposite to the plasma chambers that is positioned so that the liquid crystal layer is interposed. Thus, the liquid crystal layer is operated.
The plasma addressed electro-optical display has a multiplicity of pairs of cathode electrodes and anode electrode placed in a line to serve as discharge channels for performing a lateral scan. FIG. 1 shows the foregoing state, in which anode electrodes 102 and cathode electrodes 103 are alternately disposed in a region surrounded by a frit seal 101. Each pair of the anode electrode 102 and the cathode electrode 103 forms one discharge channel.
In the above-mentioned structure, discharge is required to take place between the anode electrode 102 and the cathode electrode 103 in one pair. However, the cathode electrodes 103 in adjacent channels sometimes undesirably perform a discharge.
FIG. 2 is an enlarged view of a portion in which the cathode electrodes 103 extend beyond the anodes 102 and the barrier ribs 104. If regions in each of which a barrier rib 104 for separating the channels from each other is not formed exist, the adjacent cathode electrodes 103 perform an undesirable discharge in the region having no barrier rib 104 for separating the channels from each other.
The foregoing discharge is unnecessary for the operation of the panel and damages the devices for operating the cathode electrodes 103. The unnecessary discharge sometimes causes heat damage to the electrodes in the panel and failure of the drive devices.